The present invention relates to a reducing lens system and more particularly to a lens system in which an original paper to be copied is projected with reduction in its size while keeping constant the distance between the surface of the original paper and the surface of the projection as well as the dimensions of the surface of the original paper and the surface of the projection.
Reducing lens systems of high speed having a relatively large aperture ratio have been known as being conventional, but there has not existed such a lens system that has the vignetting factor of 100% in order to keep the brightness of the image to its peripheral portions.